Gravel-associated organic material is important to quantify soil carbon and nitrogen stocks to depth in an agricultural cropping soil
Clive A. Kirkby A , John A. Kirkegaard A and Alan E. Richardson
A *
+ Author Affiliations
- Author Affiliations
A CSIRO Agriculture & Food, GPO Box 1700, Canberra, ACT 2601, Australia.
Soil Research 60(3) 224-233 https://doi.org/10.1071/SR21140
Submitted: 1 June 2021 Accepted: 7 September 2021 Published: 16 November 2021
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)
Abstract
Context: Gravel is a common constituent in soil and is routinely excluded when estimating soil carbon (C) and nitrogen (N) stocks.
Aims: We investigated the contribution that the gravel fraction (>2 mm) makes to C and N stocks in an agricultural soil.
Methods: The amount of gravel and the C and N content of gravel-associated organic matter (OM) was assessed to 180 cm in a long-term cropping soil with differing nutrient treatments.
Key results: Gravel-associated C and N accounted for ∼5% of the total C and N stocks in the upper layers (0–30 cm) of soil and up to 40% below 100 cm. The C:N ratio of the gravel-associated OM was similar to that in fine earth fraction (FEF) soil, with C:N ratio of ∼13 in surface layers to ∼8 at depth.
Conclusions: We estimated that 19% and 23% of the total stock of C and N, respectively, were associated with gravel over the whole soil profile. In the two nutrient treatments, with differing C and N stocks in the FEF, gravel-associated OM accounted for 9.3–10.6 t C ha−1 and 1.1–1.3 t N ha−1.
Implications: Our work highlights the significance of gravel in contributing to soil OM and the importance of sampling to depth to estimate soil C and N stocks. Importantly, disregard of the gravel fraction results in an underestimation of total soil C and N, which has implications for the accounting of C in agricultural soils and for the development of strategies to sequester soil C.
Keywords: carbon, C:N ratio, coarse fraction, gravel, sequestration, soil, SOM, stoichiometry.
References
Bauhus J, Khanna PK, Hopmans P, Weston C (2002) Is soil carbon a useful indicator of sustainable forestsoil management? – a case study from native eucalypt forests of south-eastern Australia. Forest Ecology and Management 171, 59–74.| Is soil carbon a useful indicator of sustainable forestsoil management? – a case study from native eucalypt forests of south-eastern Australia.Crossref | GoogleScholarGoogle Scholar |
Coonan EC, Kirkby CA, Kirkegaard JA, Amidy MR, Strong C, Richardson AE (2020) Microorganisms and nutrient stoichiometry as mediators of soil organic matter dynamics. Nutrient Cycling in AgroEcosystems 117, 273–298.
| Microorganisms and nutrient stoichiometry as mediators of soil organic matter dynamics.Crossref | GoogleScholarGoogle Scholar |
Corti G, Ugolini FC, Agnelli A, Certini G, Cuniglio R, Berna F, Fernandez MJ (2002) The soil skeleton, a forgotten pool of carbon and nitrogen in soil. European Journal of Soil Science 53, 283–298.
| The soil skeleton, a forgotten pool of carbon and nitrogen in soil.Crossref | GoogleScholarGoogle Scholar |
Cromack K, Miller RE, Helgerson OT, Smith RB, Anderson HW (1999) Soil carbon and nutrients in a coastal Oregon douglas-fir plantation with red alder. Soil Science Society America Journal 63, 232–239.
| Soil carbon and nutrients in a coastal Oregon douglas-fir plantation with red alder.Crossref | GoogleScholarGoogle Scholar |
Department of the Environment (2014) Carbon farming initiative, soil sampling and analysis, methods and guidelines. Department of the Environment, Australian Government. Available at https://www.scu.edu.au/media/scueduau/eal/documents/Carbon-farming-initiative-soil-sampling-and-analysis-method-guidelines.pdf [accessed December 2020]
FAO (2020) ‘A protocol for measurement, monitoring, reporting and verification of soil organic carbon in agricultural landscapes, GSOC-MRV Protocol’. (FAO: Rome).
| Crossref |
Harrison RB, Adams AB, Licata C, Flaming B, Wagoner GL, Carpenter P, Vance ED (2003) Quantifying deep-soil and coarse-soil fractions: avoiding sampling bias. Soil Science Society America Journal 67, 1602–1606.
| Quantifying deep-soil and coarse-soil fractions: avoiding sampling bias.Crossref | GoogleScholarGoogle Scholar |
Harrison RB, Footen PW, Strahm BD (2011) Deep soil horizons: contribution and importance to soil carbon pools and in assessing whole-ecosystem response to management and global change. Forest Science 57, 67–76.
| Deep soil horizons: contribution and importance to soil carbon pools and in assessing whole-ecosystem response to management and global change.Crossref | GoogleScholarGoogle Scholar |
Homann PS, Remillard SM, Harmon ME, Bormann BT (2004) Carbon storage in coarse and fine fractions of pacific northwest old-growth forest soils. Soil Science Society America Journal 68, 2023–2030.
| Carbon storage in coarse and fine fractions of pacific northwest old-growth forest soils.Crossref | GoogleScholarGoogle Scholar |
ISRIC (2002) Procedures for soil analysis – technical paper 09 (6th edition). ISRIC (International Soil Reference and Information Centre), Wageningen, The Netherlands.
Isbell RF (2002) ‘The Australian soil classification’. Australian soil and land survey handbook, Series 4. (CSIRO Publishing: Melbourne, Australia).
| Crossref |
James JN, Devine WD, Harrison RB, Terry TA (2014) Deep soil carbon: quantification and modeling in subsurface layers. Soil Science Society of America Journal 78, S1–S10.
| Deep soil carbon: quantification and modeling in subsurface layers.Crossref | GoogleScholarGoogle Scholar |
Kirkby CA, Kirkegaard JA, Richardson AE, Wade LJ, Blanchard C, Batten G (2011) Stable soil organic matter: a comparison of C:N:P:S ratios in Australian and other world soils. Geoderma 163, 197–208.
| Stable soil organic matter: a comparison of C:N:P:S ratios in Australian and other world soils.Crossref | GoogleScholarGoogle Scholar |
Kirkby CA, Richardson AE, Wade LJ, Conyers M, Kirkegaard JA (2016) Inorganic nutrients increase humification efficiency and C-sequestration in an annually cropped soil. PLoS ONE 11, e0153698
| Inorganic nutrients increase humification efficiency and C-sequestration in an annually cropped soil.Crossref | GoogleScholarGoogle Scholar | 27144282PubMed |
Kirkegaard JA, Angus JF, Gardner PA, Muller W (1994) Reduced growth and yield of wheat with conservation cropping. I. Field studies in the first year of the cropping phase. Australian Journal of Agricultural Research 45, 511–528.
| Reduced growth and yield of wheat with conservation cropping. I. Field studies in the first year of the cropping phase.Crossref | GoogleScholarGoogle Scholar |
Lal R (2004) Soil carbon sequestration to mitigate climate change. Geoderma 123, 1–22.
| Soil carbon sequestration to mitigate climate change.Crossref | GoogleScholarGoogle Scholar |
Lal R (2006) Enhancing crop yields in the developing countries through restoration of the soil organic carbon pool in agricultural lands. Land Degradation & Development 17, 197–209.
| Enhancing crop yields in the developing countries through restoration of the soil organic carbon pool in agricultural lands.Crossref | GoogleScholarGoogle Scholar |
Liang C, Amelung W, Lehmann J, Kästner M (2019) Quantitative assessment of microbial necromass contribution to soil organic matter. Global Change Biology 25, 3578–3590.
| Quantitative assessment of microbial necromass contribution to soil organic matter.Crossref | GoogleScholarGoogle Scholar | 31365780PubMed |
Liu S, Wei Y, Post WM, Cook RB, Schaefer K, Thornton MM (2013) The unified North American soil map and its implication on the soil organic carbon stock in North America. Biogeosciences 10, 2915–2930.
| The unified North American soil map and its implication on the soil organic carbon stock in North America.Crossref | GoogleScholarGoogle Scholar |
Perruchoud D, Walthert L, Zimmermann S, Lüscher P (2000) Contemporary carbon stocks of mineral forest soils in the Swiss Alps. Biogeochemistry 50, 111–136.
| Contemporary carbon stocks of mineral forest soils in the Swiss Alps.Crossref | GoogleScholarGoogle Scholar |
Poesen J (1990) Erosion process research in relation to soil erodibility and some implications for improving soil quality. In ‘Soil degradation and rehabilitation in Mediterranean environmental conditions’. (Eds J Albaladejo, MA Stocking, E Diaz) pp. 159–170. (C.S.I.C.: Murcia, Spain)
Richardson AE, Kirkby CA, Banerjee S, Kirkegaard JA (2014) The inorganic nutrient cost of building soil carbon. Carbon Management 5, 265–268.
| The inorganic nutrient cost of building soil carbon.Crossref | GoogleScholarGoogle Scholar |
Rumpel C, Kögel-Knabner I (2011) Deep soil organic matter—a key but poorly understood component of terrestrial C cycle. Plant and Soil 338, 143–158.
| Deep soil organic matter—a key but poorly understood component of terrestrial C cycle.Crossref | GoogleScholarGoogle Scholar |
Scharlemann JPW, Tanner EVJ, Hiederer R, Kapos V (2014) Global soil carbon: understanding and managing the largest terrestrial carbon pool. Carbon Management 5, 81–91.
| Global soil carbon: understanding and managing the largest terrestrial carbon pool.Crossref | GoogleScholarGoogle Scholar |
Schlesinger W (1984) Soil organic matter: a source of atmospheric CO2. In ‘The role of terrestrial vegetation in the global carbon cycle: measurements by remote sensing’. (Eds GM Woodwell) pp. 111–127. (SCOPE, John Wiley & Sons)
Smith P, Soussana J, Angers D, Schipper L, Chenu C, Rasse DP, Batjes NH, van Egmond F, McNeill S, Kuhnert M, Arias-Navarro C, Olesen JE, Chirinda N, Fornara D, Wollenberg E, Álvaro-Fuentes J, Sanz-Cobena A, Klumpp K (2020) How to measure, report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal. Global Change Biology 26, 219–241.
| How to measure, report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal.Crossref | GoogleScholarGoogle Scholar | 31469216PubMed |
Stolbovoy V, Montanarella L, Filippi N, Jones A, Gallego J, Grassi G (2007) ‘Soil sampling protocol to certify the changes of organic carbon stock in mineral soil of the European Union. Version 2’. (Office for Official Publications of the European Communities: Luxembourg)
Ugolini FC, Corti G, Agnelli A, Piccardi F (1996) Mineralogical, physical and chemical properties of rock fragments in soil. Soil Science 161, 521–542.
| Mineralogical, physical and chemical properties of rock fragments in soil.Crossref | GoogleScholarGoogle Scholar |
Wang M, Su Y, Yang X (2014) Spatial distribution of soil organic carbon and its influencing factors in desert grasslands of the Hexi corridor, northwest China. PLoS ONE 9, e94652
| Spatial distribution of soil organic carbon and its influencing factors in desert grasslands of the Hexi corridor, northwest China.Crossref | GoogleScholarGoogle Scholar | 24732375PubMed |
Whitney N, Zabowski D (2004) Total soil nitrogen in the coarse fraction and at depth. Soil Science Society America Journal 68, 612–619.
| Total soil nitrogen in the coarse fraction and at depth.Crossref | GoogleScholarGoogle Scholar |
Zabowski D, Whitney N, Gurung J, Hatten J (2011) Total soil carbon in the coarse fraction and at depth. Forest Science 57, 11–18.
| Total soil carbon in the coarse fraction and at depth.Crossref | GoogleScholarGoogle Scholar |
